Rare V-8 Performance History, Part 4

Musclecar Mania 1966 - 1969

With the brand-new Mark IV big-block 396 replacing the veteran 409 in February 1965, what could Chevrolet Engineering possibly pull next from it superb bag of ultra-performance tricks?

The solid lifter Mark IV engine could rev as high as you wanted it to. Just add the necessary valvetrain goodies, ignition, and go. Most remember 1965 for the incredible Z16 Malibu SS 396. Official internal memos said it would easily outrun and outclass the GTO.

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Second Son of the 1963 Mystery Motor: The '66 L72, 425hp 427.

I saw my very first 396 in a yellow Z16 at Nickey Chevrolet's celebration weekend. All employees were asked to work for free. But we got to meet Dan Blocker, one of the big stars of the Bonanza TV show. He was a huge motorsports fan and he liked the yellow Z16 so much, he bought it on the spot. He even slept on a sofa in the Nickey showroom Saturday night so no one would mess with his Z16. In all, 201 Z16s were built (200 hardtops and one convertible), strictly for media, high-profile people, dignitaries, plus lore has it, a few GM and Chevrolet VIPs. This was a sensational machine.

The total number of 396 full-size Chevys was 55,454. Sales of the L72 425hp 396 big car totaled only 1,838. They were uncommon when new and are super rare today. The 396/425hp Corvettes totaled 2,157. In the Chevelle department, there were 13,593 L74 300hp 327s and 6,021 L79 350hp 327s. The L79 was a sweet-running engine, capable of 5,800 rpm. With its quiet factory mufflers and resonators, it was a sleeper. You could barely hear its rumpty-rumpty idle quality.

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'67 COPO L72 425hp 427 Chevelle. Total unknown.

The '65 Chevy II quietly ordered 324 L30, 250 -hp 327 engines. The L74, 300hp 327s Chevy IIs totaled 319. Few knew these two 327 RPOs even existed. Both are ultra rare today. Either of these 327 engines in the Chevy II, Chevelle and big car could be had with an automatic or manual transmission-three- or four-speed.

Sales dwindled in 1965-we believe mainly because a ton of young male buyers got drafted into the Armed Forces.

By year-end, the 409 engine was missed per se, but everyone knew the Mark IV big-block was truly a superior engine. Since 1964, the W-motor 348 and 409s began their quest as good Stock Eliminator class engines.

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'66 L35, 325hp 396 workhorse. Hundreds of thousands sold during its production run. Very agreeable to hopping up. We got 502 hp with cam, intake, carb, headers, ignition in stock short-block, and heads.

1966Chevrolet engineers stroked the 396 to 427 cubic inches to take full advantage of NASCAR's cubic-inch limit. The new L72 425hp 427 was available in any full-size Chevrolet and Corvette. This engine was originally rated at 450 hp, but then some smart staffer mentioned "car insurance," so the same rating given to the L78 396 was kept. (It should be noted that the Corvette's hydraulic lifter 427 was rated at 400hp when it debuted and was derated to 390hp at the same time as the 450-hp rating went down.)

How does the same engine with 31 more cubic inches retain the same "suggested horsepower rating?" No...one...said...a...word. The Chevrolet dyno cells and proving grounds were testing 427 and prototype 454 engines in every configuration imaginable. What a time to work for Chevrolet Engineering.

Also new for 1966 was the super slick "SS 396" Chevelle and the L79 350-hp 327 Nova. Chevrolet Motor Division truly had a "full house," with no powerplant or accessory weaknesses in 1966. Since 1965, all the high-performance Chevy cars came with a beefy 12-bolt differential. Many were bought new over-the-counter and put in older Chevys.

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What's an oval port, you ask? On smooth-idle big-block engines, the intake ports are oval shaped. On high-performance, solid lifter engines, the ports are rectangular.

Total '66 V8 El Camino sales were 20,331. Total '66 V8 Chevelle sales were 238,371. There were 1,865 SS Chevelles and El Caminos that had the L34 350hp 396, and 3,099 had the L78, 375hp 396. The remaining 67,308 had the base 325hp 396. For sure, no one in any of the Chevrolet engine or vehicle assembly lines was standing around.

The L79 Chevy II was an immediate legend. An East Coast magazine correctly bragged how tough and quick the new '66 426 Mopar Street Hemi was. But after a few months of stoplight performance testing, they said the Street Hemi was "hot all right, but not quite as hot as the average 425hp 427 Corvette or 350hp 327 Chevy II."

'66 L35, 325hp 396 workhorse. Hundreds of thousands sold during its production run. Very agreeable to hopping up. We got 502 hp with cam, intake, carb, headers, ignition in stock short-block, and heads.

What's an oval port, you ask? On smooth-idle big-block engines, the intake ports are oval shaped. On high-performance, solid lifter engines, the ports are rectangular.

This pinnacle-perfect L34, 350hp 396 also sold in the hundreds of thousands during its production run. It got a 25-hp boost over the L35 with a slightly hotter hydraulic camshaft and a Holley carburetor.

The L78, 375hp 396 was very powerful and it revved higher and better than any other RPO big-block. It was also rated at 425 hp in the '65 Corvette and big car. Every SC reader should go for a test-ride in one!

The late, great Dick Harrell lost his life in a Camaro Funny Car accident in 1971. A decade earlier he was known as "Mr. Chevrolet" on the dragstrip. He was 100 percent devoted to Chevy. Here is a trick dual-quad big-block that his Kansas City shop built into a Chevelle, circa 1968.

Here is a real-deal '69 COPO 9561 L72 425hp 427 Camaro engine. Somewhere between 512 and 700 of these powerful Camaros were sold. Putting a 427 into a '69 Camaro rates as one of the top owner update modifications of all time. This car was also one of the scariest of all time to drive on the street. Some 72 iron 427 COPOs 9561 are documented as alive and well today.

The 290hp 302 Z/28 small-block was rare in 1967 and 1968, but plentiful in 1969. It needed steep gearing to run strong, but what a blast to drive. They could outrun many a so-called musclecar.

This '69 Yenko Chevelle with L72 425hp 427 was heavier than a Camaro, but it launched much better with its rear control arms and coil springs. Having a full frame, it did not dart around due to chassis flex caused by torrid big-block power.

This is one of the 69 '69 ZL1 aluminum 427 race-engine Camaros. With a 13.0:1 compression ratio, a full-race camshaft and a factory "chambered" exhaust (no mufflers), it sounds like nothing you have ever heard before. It should not be street-driven due to the big duration camshaft, high compression and low-speed overheating. The ZL1 COPO 9560 option cost $4,160. The base price of a '69 V-8 Camaro sport coupe was $2,727.